PIC17C75X
TABLE 10-1: PORTA FUNCTIONS
Buffer
Name
Bit0
Function
Type
RA0/INT
bit0
bit1
ST
ST
Input or external interrupt input.
RA1/T0CKI
Input or clock input to the TMR0 timer/counter, and/or an external interrupt
input.
2
RA2/SS/SCL
RA3/SDI/SDA
bit2
bit3
ST
ST
Input/Output or slave select input for the SPI or clock input for the I C bus.
Output is open drain type.
2
Input/Output or data input for the SPI or data for the I C bus.
Output is open drain type.
RA4/RX1/DT1
RA5/TX1/CK1
RBPU
bit4
bit5
bit7
ST
ST
—
Input/Output or USART1 Asynchronous Receive or
USART1 Synchronous Data.
Input/Output or USART1 Asynchronous Transmit or
USART1 Synchronous Clock.
Control bit for PORTB weak pull-ups.
Legend: ST = Schmitt Trigger input.
TABLE 10-2: REGISTERS/BITS ASSOCIATED WITH PORTA
Value on
all other
resets
Value on
POR,
BOR
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
(Note1)
RA5/
RA4/
RA3/
RA2/
0-xx xxxx 0-uu uuuu
10h, Bank 0
PORTA
RBPU
—
RA1/T0CKI RA0/INT
TX1/CK1 RX1/DT1 SDI/SDA SS/SCL
05h, Unbanked T0STA
INTEDG T0SE
T0CS
SREN
TXEN
PS3
PS2
—
PS1
FERR
—
PS0
—
0000 000- 0000 000-
0000 -00x 0000 -00u
0000 --1x 0000 --1u
13h, Bank 0
15h, Bank 0
RCSTA1
TXSTA1
SPEN
CSRC
RC9
TX9
CREN
SYNC
OERR
TRMT
RC9D
TX9D
—
Legend: x= unknown, u= unchanged, -= unimplemented reads as '0'. Shaded cells are not used by PORTA.
Note 1: Other (non power-up) resets include: external reset through MCLR and the Watchdog Timer Reset.
1997 Microchip Technology Inc.
Preliminary
DS30264A-page 67
MICROCHIP [ MICROCHIP ]
